Process of making composite material.



UNITED STATES PATENT OFFICE.

DANIEL J. OCONOR, 'J'R., OF PITTSLBIIRGH, PENNSYLVANIA, ASSIGNOR '10 WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- PBOCESS OF MAKING COMPOSITE MATERIAL.

' Patented Nov. 12, 1918.

VANIA.

1,284,432. Specification of Letters Patent.

No Drawing. Application filed February 1, 1913 Serial No. 745,616.

To all whom it may concern: I

Be it known that I, DANIEL J. OCoNoa, J r., a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a' new and useful Improvement in Processes of Making Composite Material, of which the following is a specification.

My invention has particular reference to methods of manufacturing composite materials, such as cardboard.

One object of my invention is to provide an insulating material which is light, strong, and insoluble and has a high dielectric strength.

,Another object is to provide a simple and efficient process of producing an insulating material of the above-indicated character in large quantities as a commercial product.

Heretofore, insulation material such as cardboard, composed of layers of paper glued together, has proved more or less unsatisfactory because of various defects, such as absorpt1on of moisture from the atmosphere, inability to resist heat and chemical action, and lack of physical strength. Insulatin material to be used in connection with switc boards and wireless telegraph and other high voltage installations, must be free from these defects, and, in addition, must possess high dielectric strength. My invention provides a process of manufacturing an insulating1 material possessing these qualities in a igh degree.

In carrying out this process, any suitable fabric, such as paper, muslin, or other cloth, and fibrous or porous materlal of any kind may be used. f paper is used, the fabric preferably baeren paper, kraft paper or the so called micafohum paper Whlch has a coating of mica flakes, of any desired thickness, is first coated on one Slde with an adhesive liquid insulating material, suitably that known as bakelite and consisting of a condensation product of phenols and formaldehyde. The coating operation is performed by passing the paper between two rollers, the bottom one of which dips into the liquid material which is contained in atank. The thickness of the coating retained by the paper is regulated by varying the distance between the two rollers and by altering the viscosity of the liquid. The paper is then dried by passing it over a series of rollers in a steam-heated oven. The prepared paper is cut into sheets of any desired size but, for convenience, preferably 18"x36" or 36"x36, as desired. A plate is built up to the required thickness by placing the sheets together with the untreated side of each sheet next to the treated side of the adjacent sheet, the number of sheets required for any desired thickness of finished material having been previously determined. The upper sheet 1s preferably placed with its treated slde down, in order t at both the top and the bottom of the finished plate will present untreated faces.

The built-up plate is then placed between thin sheet steel plates on which has been rubbed a small amount of machine oil. Any deslred number of the steel plates carrying the sheets of paper are placed between the platens of a hydraulic press which have been previously heated, (preferably by steam. The press is closed an pressure a plied, which may be as high as 800 poun s per square lnc or approximately, 535 tons on an area 36"x36". Satisfactory results have also been obtained by using lower pressures. Heat is applied, preferably by steam, while the materlal is in the press. The pressure is kept constant during the period of heating and the subsequent period of cooling. These periods are varied accordin to the thickness .of the plate approximate y in accordance with the following table:

Thickness Time under Time of of plate. steam. cooling.

to 15 min. 10 min. 3 I! to g u u I! II (l I g to 1}" 1.00 hr. 25

The effect of heating and pressing the plate is to firmly cement together the sheets of paper and to further impre ate the paer with the bakelite. The p ate is transormed into a hard and compact mass.

After cooling, the plates of insulation are I removed from the press and then clamped between steel plates to prevent warping during baking, which is the last step in the process and which is employed for the purpose of removing any moisture remaining in the insulation and for transforming the bakelite completely into its infusible and insoluble condition. The plates are then placed in ovens, air pressure of approximately 140 pounds per square inch is applied, and the temperature is regulated between 100 and 140 C.- The air pressure my be omitted if the plates are clamped su ciently tight. These conditions are maintained for approximately eight hours, during which time any remaining moisture is expelled. The plates are then removed from the oven and the finished product is allowed to cool.

While the process above described is that used for making plates, the insulating material may be produced in the form of channel pieces'or tubes that are cylindrical or rectangular in cross section or of other shape, as desired, by pressing in forms of the proper shape.

The resultant material has a specific gravity of approximately 1.25. It is practically non-absorbent, even when soaked in hot water, and is insoluble. Consequently, there is no tendency for any given structure of this material to change its dimensions when subjected to moisture or atmospheric conditions. The ordinary reagents have no appreciable effect under ordinary conditions. The substance will withstand a constant temperature of 150 C. without deterioration and up to 300 C., if temporary. The tensile strength of this insulating material is approximately 20,000 pounds per square inch, which exceeds that of wood, fiber and other similar materials. The material is very hard, having an average of more than 40 by the Brinell test. It can be turned and bored in the same manner as Wood, adapting it for various shapes and purposes. In addition to the above named qualities, the dielectric strength is high, averaging 820 volts per mil. for plates to i" in thickness.

While I have described the process in full, it is obvious that the details thereof above given may be varied as conditions require, without departing from the spirit of my inventlon.

It is particularly understood that the term fabric, as used in the specification and claims, is not limited to paper, which is described and claimed specifically, but is used in its broad sense to include muslin, or other cloth, asbestos, orany other fibrous or porous material.

I claim as my invention:

1. The process of making a laminated composition that consists in coating one side of each ofa plurality of sheets of fibrous material with a phenolic condensation product, superposing the coated sheets, applying heat and pressure to the superposed sheets, and then applying a greater degree of heat and a lower pressure.

2. The process of making a laminated composition that consists in coating one side of each of a plurality of sheets of fibrous material with a phenolic condensation product, superposing the coated sheets successively heating and cooling the superposed Lac-1,43%

sheets while'under relatively high pressure and then heating the resulting plate while under relatively low pressure.

The process of manufacturing insulating material which consists in superposing sheets of paper coated with a phenolic condensation product, applying to said sheets of paper a pressure between 100 lbs. and 200 lbs. per square inch and applying heat While the pressure is maintained,-cooling the plate thus formed, and then applying an increased heat to the plate while under pressure.

4. The process of manufacturing insulating material which consists in supcrposing sheets of paper coated with varnish containing a phenolic condensation product, applying thereto a pressure of 100 lbs. to 800 lbs. per square inch, heating and cooling the plate thus formed, while under said pressure, and then heating to a temperature of 100 to 170 C., while under pressure.

5. The process of making a laminated composition that comprises treating a plurality of sheets of fibrous material with a phenolic condensation product, superposing the treated sheets, stacking a plurality of oiled metallic plates alternated with sets of the said superposed sheets, subjecting the stacked material to heat and pressure, cooling the stacked material while under pressure, and baking the composite sheets.

6. The process of making a laminated comtallic plates alternated with sets of the said superposed sheets, subjecting the stacked material simultaneously to heat and to pressure not substantially exceeding 800 pounds per square inch, cooling the stacked material under pressure, and thereafter heating the composite material under lower pressure.

7. The process of making a composite product that consists in applying to each of a plurality of sheets of fibrous material an adhesive material that is capable of being solidified by heat and pressure, superposing the treated sheets, applying heat and pressure to the superposed sheets, and then applying a greater degree of heat and a lower pressure. p

8. The process of manufacturing a composite product which consists in superposing layers of coated fabric, simultaneously heating and pressing the said layers, cooling the material thus formed and again subjecting the material to pressure and heat.

9. The process of manufacturing a composite product which consists in superposing a plurality of sheets of fibrous material associated with a phenolic condensation product, applying heat and pressure to the superposed sheets, discontinuing the said heating and pressing step and subsequently applying a lower pressure and a greater degree of heat to the product of the first heating and pressing stetp.

10. The process 0 manufacturing a composite product which consists in superposing a plurality of sheets of fibrous material associated with an adhesive material that is adapted to harden under the influence of heat and pressure, applying heat and pressure to the superposed sheets, discontinuing the said heating and pressing step and subsequently applying a lower pressure and a reater degree of heat to the product of the rst heating and pressing step.

11. The process of manufacturing a nonplaniform article which consists in superposing a plurality of layers of fibrous material associated with an adhesive substance that is adapted to harden under the influence of heat and pressure into a substantially infusible and insoluble condition, and mol ing the superposed layers by means of a form of the proper shape while applying pressure and heat to compact and harden the materials. e

12. The process of manufacturing a nonplaniform article which consists in super-. posing a plurality of layers of fibrous material associated with a phenolic condensation product and molding the superposed layers by means of a form of the proper shape while applying pressure and heat to compact and harden the materials.

In testimony whereof, I have hereunto subscribed my name this th day of J anuary, 1913.

DANIELJ. OCONOR, JR.

Witnesses B. B. Hmns, M. C. MERZ. 

